1. Field of the Invention
The present invention relates to fuel injection valve to inject fuel to a heat engine.
2. Description of Related Art
A conventional fuel injection valve disclosed in JP-A-2001-500218 corresponding to U.S. Pat. No. 6,196,193 includes a nozzle, a control valve, an actuator, and a control chamber. Typically, the nozzle has a needle that opens and closes an injection orifice. The control valve is provided inside a valve chamber for selectively connecting the valve chamber with a low-pressure fuel passage or with a high-pressure fuel passage. The actuator actuates the control valve. The control chamber is always communicated with the valve chamber through a communication passage. Fuel pressure in the control chamber biases the needle in a valve closing direction for closing the injection orifice. The control valve controls pressure in the control chamber for controlling the opening and closing the valve of the nozzle.
Also, the following structure is adopted such that a speed of nozzle for opening and closing the valve can be set independently. In other words, at the time of state, where the communication between the valve chamber and the high-pressure fuel passage is allowed, high pressure fuel in the high-pressure fuel passage is introduced into the control chamber only through the communication passage. More particularly, the fuel injection valve includes an out orifice in a low-pressure fuel passage, and an in orifice in the high-pressure fuel passage. According to this, a valve opening speed of the nozzle for opening the injection orifice can be set by the out orifice, and a valve closing speed of the nozzle for closing the injection orifice can be set by the in orifice. Thus, the speed for opening and closing the valve (injection orifice) of the nozzle can be set independently, and flexibility of setting the speed for opening and closing the valve of the nozzle is remarkably high.
However, in the fuel injection valve described in JP-A-2001-500218, as shown in FIG. 8, pressure pulsation is generated in the control chamber at a time of a valve opening of the nozzle. As a result, the needle resonates with pressure pulsation to oscillate, and thereby disadvantageously being lifted. At this time, a lift amount of the needle is not proportional to a drive pulse duration (corresponding to a command value for an injection period). As a result, as shown in FIG. 9, a characteristic curve of the fuel injection quantity with respect to the drive pulse duration disadvantageously is not linear.